Đáp án+giải thích các bước giải:
Bài 9:
a)
$\dfrac{36(x-2)^3}{32-16x}=\dfrac{36(x-2)^3}{16(2-x)}=\dfrac{36(x-2)^3}{-16(x-2)}$ $=\dfrac{9(x-2)^2}{-4}$
b)
$\dfrac{x^2-xy}{5y^2-5xy}=\dfrac{x(x-y)}{5y(y-x)}=\dfrac{x(x-y)}{-5y(x-y)}=\dfrac{x}{-5y}$
Bài 10:
$\dfrac{x^7+x^6+x^5+x^4+x^3+x^2+x+1}{x^2-1}$ $=\dfrac{(x^7+x^6)+(x^5+x^4)+(x^3+x^2)+(x+1)}{(x-1)(x+1)}$ $=\dfrac{x^6(x+1)+x^4(x+1)+x^2(x+1)+(x+1)}{(x-1)(x+1)}$ $=\dfrac{(x+1)(x^6+x^4+x^2+1)}{(x-1)(x+1)}$ $=\dfrac{x^6+x^4+x^2+1}{x-1}$
